Mechanistic study on the inhibition of Staphylococcus epidermidis biofilm by agrC-specific binding polypeptide

Considering the wide-spread misuse of antibiotics, the development of new antibacterial drugs may effectively prevent the emergence of antibiotic resistance in bacteria. The understanding of the mechanism underlying the agrC-specific binding polypeptide-mediated inhibition of biofilm formation may supply ideas for the development of new antibacterial drugs. cells were cultured with different concentrations (0, 100, 200, 400, 800, and 1,600 µg/mL) of agrC-specific binding polypeptide (N1) and blank (N0). Crystal violet staining was performed to test the formation of biofilms and to determine the best concentration of agrC-specific binding polypeptides, and the bacterial inhibitory concentration was also determined. At different time points (6, 12, 18, 24, and 30 h), XTT assay was used to measure bacterial viability, and the real-time quantitative polymerase chain reaction was performed to measure the expression of , , , and genes. The sulfuric acid-phenol method was used to determine polysaccharide intercellular adhesin (PIA) levels. The biofilm formation ability of was the lowest after treatment with 800 µg/mL agrC-specific binding polypeptide. After 6 h of culture, agrC-specific binding polypeptide upregulated the expression of , , , and and increased the bacterial viability. However, the polypeptide downregulated the expression of , , , and and inhibited growth and PIA formation after 12 h of culture. Although agrC-specific binding polypeptide upregulated the expression of , , , and after 18 h, they inhibited bacterial growth and PIA formation. Thus, agrC-specific binding polypeptide could downregulate the expression of , , , and and inhibit PIA formation by after 12 h, demonstrating its transient inhibitory effects on the biofilm formation ability of . Its effective concentration was 800 µg/mL.